1. Technical Field
Embodiments of the present invention relate to a fluid ejection device, and a medical instrument including the fluid ejection device.
2. Related Art
A fluid ejection device capable of excising, incising, and crushing living tissue has excellent characteristics when used as a surgical instrument. A low probability of heat damage and preservation of blood vessels including capillaries are examples of these characteristics.
During surgery, a surgery target may become obscured from view while using the fluid ejection device. A certain type of fluid ejection device has a suction tube which sucks and removes the ejected liquid, excised tissue or the like remaining on the surgery target so as to ensure that the surgery target remains visible during surgery.
This type of fluid ejection device includes an ejection tube through which high-pressure fluid is ejected. The ejection tube is disposed within a suction channel of a suction tube in such a position so as to be concentric with the suction channel (for example, see JP-A-1-313047).
Another example of the fluid ejection device has an ejection tube through which high-pressure fluid is ejected. This ejection tube is inserted into a suction tube eccentrically with respect to the inner circumferential surface of the suction tube (for example, see JP-A-6-90957).
A further example of the fluid ejection device is equipped with a volume varying unit which rapidly varies the volume of a fluid chamber so as to convert the fluid into a pulsed fluid. The fluid is thus ejected in pulses at high speed through an ejection opening (for example, see JP-A-2008-82202).
According to the fluid ejection devices disclosed in JP-A-1-313047 and JP-A-6-90957, however, the ejection tube vibrates when fluid is ejected in pulses at high speed when using the technology disclosed in JP-A-2008-82202. More specifically, the ejection tube provided within the suction tube is not supported or fixed except at the root of the ejection tube. As a result, vibrations occur at the tip of the ejection tube when fluid is ejected in pulses at high speed. Several problems arise from the vibrations that occur at the tip of the ejection tube. For example, there is a decrease in the positional accuracy of the fluid ejection. In addition, vibration noise is generated by the interference between the ejection tube and the suction tube into which the ejection tube is inserted.
To overcome these problems, a structure has been adopted which includes a support member within the suction tube to firmly support the ejection tube. However, this structure is complicated. In addition, this structure deteriorates the maneuverability of the fluid ejection device due to the increased size and weight of the fluid ejection device resulting from this structure.